A metal chain that is fastened to the piece of equipment and a fixed point as a secondary attachment. This acts as a backup, preventing the item from falling if the primary attachment fails. A secondary attachment is a legal requirement although chains are being phased out in preference to safety wires.

(1) A secondary support line, usually of chain, that supports a fire curtain or other device when the primary support cable become slack for any reason. (2) The extra weight of fire curtain safety chains helps the fire curtain accelerate at the start of its travel.

A safety chain is a secondary closure (usually on a fine bracelet or watch) that is used in case the primary clasp opens, preventing the loss of the bracelet. It is usually a chain that is permanently attached to one side of the bracelet, and attaches to the other side with a spring ring clasp (or other type of clasp). On the Miriam Haskell cuff bracelet above, the safety chain is located on the lower left of the picture.